The objective of this research project is to study existing vaccine carrier systems such as microspheres and adjuvant formulations. We have begun a study of the structure and reactivity of the promising new QS21. This particular adjuvant lends itself to structure determination, unlike most adjuvants, since it is a single chemical compound. Furthermore, a wealth of related saponins exhibit adjuvanticity but are highly toxic. This creates an opportunity for us to learn about the relationship between adjuvanticity and toxicity in these class of compounds. We have also began work on microencapsulations of antigens. We have chosen to develop microencapsulations with polysaccharides. These encapsulations can be performed under mild conditions preventing the denaturing of antigens. Furthermore, the capsule material itself may act as an antigen, producing a combination vaccine. Lastly, we have started to develop a program to look at the interaction of Alum with transferrin and how that affects the adjuvant properties of Alum adsorbed vaccines.